1. Field of the Invention
The present invention relates to a multi-band antenna.
2. Description of the Related Art
Recently, a wireless communication function is mounted in various electronic devices. Also, there are proposed an increasing number of devices in which one electronic device complies with a plurality of wireless communication standards. These devices need to implement an antenna which operates in a plurality of frequency bands corresponding to the respective standards. Along with downsizing of devices, the antenna which operates in a plurality of frequency bands needs to be arranged in a space as small as possible. To achieve this, one antenna needs to have a plurality of operating bands and have a desired antenna operating bandwidth.
For example, Japanese Patent No. 4710457 proposes a method of configuring a dual-band antenna which operates in two frequency bands by adding a parasitic element. Also, for example, Japanese Patent No. 4457850 or Rod Waterhouse, “Printed Antennas for Wireless Communications”, WILEY, 2007, ISBN 978-0-470-51069-8, pp. 257-279 proposes the arrangement of an antenna having a wideband antenna characteristic as a dual-band antenna or multi-band antenna.
In general, an electronic device needs to be small, so an antenna serving as a component of the electronic device also needs to be small. Since laws concerning wireless communication differ between countries, frequencies used in the respective countries are different even for the same wireless communication standard. On the assumption that electronic devices sell in all the world's countries, an antenna which achieves a very wide operating bandwidth of about 5 GHz to 6 GHz in, for example, the 5-GHz band in a wireless LAN is requested to cope with major countries. However, a conventional antenna does not fully satisfy requirements that it is compact, operates in a plurality of frequency bands, and operates in a wide band depending on the wireless standard.
The present invention provides a compact multi-band antenna capable of easily satisfying the operating frequency requirement.